dig

DIG(1)                               BIND9                              DIG(1)

NAME
       dig - DNS lookup utility

SYNOPSIS
       dig [@server] [-b address] [-c class] [-f filename] [-k filename] [-m]
           [-p port#] [-q name] [-t type] [-v] [-x addr] [-y [hmac:]name:key]
           [[-4] | [-6]] [name] [type] [class] [queryopt...]

       dig [-h]

       dig [global-queryopt...] [query...]

DESCRIPTION
       dig is a flexible tool for interrogating DNS name servers. It performs
       DNS lookups and displays the answers that are returned from the name
       server(s) that were queried. Most DNS administrators use dig to
       troubleshoot DNS problems because of its flexibility, ease of use and
       clarity of output. Other lookup tools tend to have less functionality
       than dig.

       Although dig is normally used with command-line arguments, it also has
       a batch mode of operation for reading lookup requests from a file. A
       brief summary of its command-line arguments and options is printed when
       the -h option is given. Unlike earlier versions, the BIND 9
       implementation of dig allows multiple lookups to be issued from the
       command line.

       Unless it is told to query a specific name server, dig will try each of
       the servers listed in /etc/resolv.conf. If no usable server addresses
       are found, dig will send the query to the local host.

       When no command line arguments or options are given, dig will perform
       an NS query for "." (the root).

       It is possible to set per-user defaults for dig via ${HOME}/.digrc.
       This file is read and any options in it are applied before the command
       line arguments. The -r option disables this feature, for scripts that
       need predictable behaviour.

       The IN and CH class names overlap with the IN and CH top level domain
       names. Either use the -t and -c options to specify the type and class,
       use the -q the specify the domain name, or use "IN." and "CH." when
       looking up these top level domains.

SIMPLE USAGE
       A typical invocation of dig looks like:

            dig @server name type

       where:

       server
           is the name or IP address of the name server to query. This can be
           an IPv4 address in dotted-decimal notation or an IPv6 address in
           colon-delimited notation. When the supplied server argument is a
           hostname, dig resolves that name before querying that name server.

           If no server argument is provided, dig consults /etc/resolv.conf;
           if an address is found there, it queries the name server at that
           address. If either of the -4 or -6 options are in use, then only
           addresses for the corresponding transport will be tried. If no
           usable addresses are found, dig will send the query to the local
           host. The reply from the name server that responds is displayed.

       name
           is the name of the resource record that is to be looked up.

       type
           indicates what type of query is required -- ANY, A, MX, SIG, etc.
           type can be any valid query type. If no type argument is supplied,
           dig will perform a lookup for an A record.

OPTIONS
       -4
           Use IPv4 only.

       -6
           Use IPv6 only.

       -b address[#port]
           Set the source IP address of the query. The address must be a valid
           address on one of the host's network interfaces, or "0.0.0.0" or
           "::". An optional port may be specified by appending "#<port>"

       -c class
           Set the query class. The default class is IN; other classes are HS
           for Hesiod records or CH for Chaosnet records.

       -f file
           Batch mode: dig reads a list of lookup requests to process from the
           given file. Each line in the file should be organized in the same
           way they would be presented as queries to dig using the
           command-line interface.

       -k keyfile
           Sign queries using TSIG using a key read from the given file. Key
           files can be generated using tsig-keygen(8). When using TSIG
           authentication with dig, the name server that is queried needs to
           know the key and algorithm that is being used. In BIND, this is
           done by providing appropriate key and server statements in
           named.conf.

       -m
           Enable memory usage debugging.

       -p port
           Send the query to a non-standard port on the server, instead of the
           default port 53. This option would be used to test a name server
           that has been configured to listen for queries on a non-standard
           port number.

       -q name
           The domain name to query. This is useful to distinguish the name
           from other arguments.

       -r
           Do not read options from ${HOME}/.digrc. This is useful for scripts
           that need predictable behaviour.

       -t type
           The resource record type to query. It can be any valid query type.
           If it is a resource record type supported in BIND 9, it can be
           given by the type mnemonic (such as "NS" or "AAAA"). The default
           query type is "A", unless the -x option is supplied to indicate a
           reverse lookup. A zone transfer can be requested by specifying a
           type of AXFR. When an incremental zone transfer (IXFR) is required,
           set the type to ixfr=N. The incremental zone transfer will contain
           the changes made to the zone since the serial number in the zone's
           SOA record was N.

           All resource record types can be expressed as "TYPEnn", where "nn"
           is the number of the type. If the resource record type is not
           supported in BIND 9, the result will be displayed as described in
           RFC 3597.

       -u
           Print query times in microseconds instead of milliseconds.

       -v
           Print the version number and exit.

       -x addr
           Simplified reverse lookups, for mapping addresses to names. The
           addr is an IPv4 address in dotted-decimal notation, or a
           colon-delimited IPv6 address. When the -x is used, there is no need
           to provide the name, class and type arguments.  dig automatically
           performs a lookup for a name like 94.2.0.192.in-addr.arpa and sets
           the query type and class to PTR and IN respectively. IPv6 addresses
           are looked up using nibble format under the IP6.ARPA domain.

       -y [hmac:]keyname:secret
           Sign queries using TSIG with the given authentication key.  keyname
           is the name of the key, and secret is the base64 encoded shared
           secret.  hmac is the name of the key algorithm; valid choices are
           hmac-md5, hmac-sha1, hmac-sha224, hmac-sha256, hmac-sha384, or
           hmac-sha512. If hmac is not specified, the default is hmac-md5 or
           if MD5 was disabled hmac-sha256.

           NOTE: You should use the -k option and avoid the -y option, because
           with -y the shared secret is supplied as a command line argument in
           clear text. This may be visible in the output from ps(1) or in a
           history file maintained by the user's shell.

QUERY OPTIONS
       dig provides a number of query options which affect the way in which
       lookups are made and the results displayed. Some of these set or reset
       flag bits in the query header, some determine which sections of the
       answer get printed, and others determine the timeout and retry
       strategies.

       Each query option is identified by a keyword preceded by a plus sign
       (+). Some keywords set or reset an option. These may be preceded by the
       string no to negate the meaning of that keyword. Other keywords assign
       values to options like the timeout interval. They have the form
       +keyword=value. Keywords may be abbreviated, provided the abbreviation
       is unambiguous; for example, +cd is equivalent to +cdflag. The query
       options are:

       +[no]aaflag
           A synonym for +[no]aaonly.

       +[no]aaonly
           Sets the "aa" flag in the query.

       +[no]additional
           Display [do not display] the additional section of a reply. The
           default is to display it.

       +[no]adflag
           Set [do not set] the AD (authentic data) bit in the query. This
           requests the server to return whether all of the answer and
           authority sections have all been validated as secure according to
           the security policy of the server. AD=1 indicates that all records
           have been validated as secure and the answer is not from a OPT-OUT
           range. AD=0 indicate that some part of the answer was insecure or
           not validated. This bit is set by default.

       +[no]all
           Set or clear all display flags.

       +[no]answer
           Display [do not display] the answer section of a reply. The default
           is to display it.

       +[no]authority
           Display [do not display] the authority section of a reply. The
           default is to display it.

       +[no]badcookie
           Retry lookup with the new server cookie if a BADCOOKIE response is
           received.

       +[no]besteffort
           Attempt to display the contents of messages which are malformed.
           The default is to not display malformed answers.

       +bufsize=B
           Set the UDP message buffer size advertised using EDNS0 to B bytes.
           The maximum and minimum sizes of this buffer are 65535 and 0
           respectively. Values outside this range are rounded up or down
           appropriately. Values other than zero will cause a EDNS query to be
           sent.

       +[no]cdflag
           Set [do not set] the CD (checking disabled) bit in the query. This
           requests the server to not perform DNSSEC validation of responses.

       +[no]class
           Display [do not display] the CLASS when printing the record.

       +[no]cmd
           Toggles the printing of the initial comment in the output,
           identifying the version of dig and the query options that have been
           applied. This option always has global effect; it cannot be set
           globally and then overridden on a per-lookup basis. The default is
           to print this comment.

       +[no]comments
           Toggles the display of some comment lines in the output, containing
           information about the packet header and OPT pseudosection, and the
           names of the response section. The default is to print these
           comments.

           Other types of comments in the output are not affected by this
           option, but can be controlled using other command line switches.
           These include +[no]cmd, +[no]question, +[no]stats, and
           +[no]rrcomments.

       +[no]cookie[=####]
           Send a COOKIE EDNS option, with optional value. Replaying a COOKIE
           from a previous response will allow the server to identify a
           previous client. The default is +cookie.

           +cookie is also set when +trace is set to better emulate the
           default queries from a nameserver.

       +[no]crypto
           Toggle the display of cryptographic fields in DNSSEC records. The
           contents of these field are unnecessary to debug most DNSSEC
           validation failures and removing them makes it easier to see the
           common failures. The default is to display the fields. When omitted
           they are replaced by the string "[omitted]" or in the DNSKEY case
           the key id is displayed as the replacement, e.g. "[ key id = value
           ]".

       +[no]defname
           Deprecated, treated as a synonym for +[no]search

       +[no]dnssec
           Requests DNSSEC records be sent by setting the DNSSEC OK bit (DO)
           in the OPT record in the additional section of the query.

       +domain=somename
           Set the search list to contain the single domain somename, as if
           specified in a domain directive in /etc/resolv.conf, and enable
           search list processing as if the +search option were given.

       +dscp=value
           Set the DSCP code point to be used when sending the query. Valid
           DSCP code points are in the range [0..63]. By default no code point
           is explicitly set.

       +[no]edns[=#]
           Specify the EDNS version to query with. Valid values are 0 to 255.
           Setting the EDNS version will cause a EDNS query to be sent.
           +noedns clears the remembered EDNS version. EDNS is set to 0 by
           default.

       +[no]ednsflags[=#]
           Set the must-be-zero EDNS flags bits (Z bits) to the specified
           value. Decimal, hex and octal encodings are accepted. Setting a
           named flag (e.g. DO) will silently be ignored. By default, no Z
           bits are set.

       +[no]ednsnegotiation
           Enable / disable EDNS version negotiation. By default EDNS version
           negotiation is enabled.

       +[no]ednsopt[=code[:value]]
           Specify EDNS option with code point code and optionally payload of
           value as a hexadecimal string.  code can be either an EDNS option
           name (for example, NSID or ECS), or an arbitrary numeric value.
           +noednsopt clears the EDNS options to be sent.

       +[no]expire
           Send an EDNS Expire option.

       +[no]expandaaaa
           When printing AAAA record print all zero nibbles rather than the
           default RFC 5952 preferred presentation format.

       +[no]fail
           Do not try the next server if you receive a SERVFAIL. The default
           is to not try the next server which is the reverse of normal stub
           resolver behavior.

       +[no]header-only
           Send a query with a DNS header without a question section. The
           default is to add a question section. The query type and query name
           are ignored when this is set.

       +[no]identify
           Show [or do not show] the IP address and port number that supplied
           the answer when the +short option is enabled. If short form answers
           are requested, the default is not to show the source address and
           port number of the server that provided the answer.

       +[no]idnin
           Process [do not process] IDN domain names on input. This requires
           IDN SUPPORT to have been enabled at compile time.

           The default is to process IDN input when standard output is a tty.
           The IDN processing on input is disabled when dig output is
           redirected to files, pipes, and other non-tty file descriptors.

       +[no]idnout
           Convert [do not convert] puny code on output. This requires IDN
           SUPPORT to have been enabled at compile time.

           The default is to process puny code on output when standard output
           is a tty. The puny code processing on output is disabled when dig
           output is redirected to files, pipes, and other non-tty file
           descriptors.

       +[no]ignore
           Ignore truncation in UDP responses instead of retrying with TCP. By
           default, TCP retries are performed.

       +[no]keepalive
           Send [or do not send] an EDNS Keepalive option.

       +[no]keepopen
           Keep the TCP socket open between queries and reuse it rather than
           creating a new TCP socket for each lookup. The default is
           +nokeepopen.

       +[no]mapped
           Allow mapped IPv4 over IPv6 addresses to be used. The default is
           +mapped.

       +[no]multiline
           Print records like the SOA records in a verbose multi-line format
           with human-readable comments. The default is to print each record
           on a single line, to facilitate machine parsing of the dig output.

       +ndots=D
           Set the number of dots that have to appear in name to D for it to
           be considered absolute. The default value is that defined using the
           ndots statement in /etc/resolv.conf, or 1 if no ndots statement is
           present. Names with fewer dots are interpreted as relative names
           and will be searched for in the domains listed in the search or
           domain directive in /etc/resolv.conf if +search is set.

       +[no]nsid
           Include an EDNS name server ID request when sending a query.

       +[no]nssearch
           When this option is set, dig attempts to find the authoritative
           name servers for the zone containing the name being looked up and
           display the SOA record that each name server has for the zone.
           Addresses of servers that that did not respond are also printed.

       +[no]onesoa
           Print only one (starting) SOA record when performing an AXFR. The
           default is to print both the starting and ending SOA records.

       +[no]opcode=value
           Set [restore] the DNS message opcode to the specified value. The
           default value is QUERY (0).

       +padding=value
           Pad the size of the query packet using the EDNS Padding option to
           blocks of value bytes. For example, +padding=32 would cause a
           48-byte query to be padded to 64 bytes. The default block size is
           0, which disables padding. The maximum is 512. Values are
           ordinarily expected to be powers of two, such as 128; however, this
           is not mandatory. Responses to padded queries may also be padded,
           but only if the query uses TCP or DNS COOKIE.

       +[no]qr
           Toggles the display of the query message as it is sent. By default,
           the query is not printed.

       +[no]question
           Toggles the display of the question section of a query when an
           answer is returned. The default is to print the question section as
           a comment.

       +[no]raflag
           Set [do not set] the RA (Recursion Available) bit in the query. The
           default is +noraflag. This bit should be ignored by the server for
           QUERY.

       +[no]rdflag
           A synonym for +[no]recurse.

       +[no]recurse
           Toggle the setting of the RD (recursion desired) bit in the query.
           This bit is set by default, which means dig normally sends
           recursive queries. Recursion is automatically disabled when using
           the +nssearch option, and when using +trace except for an initial
           recursive query to get the list of root servers.

       +retry=T
           Sets the number of times to retry UDP queries to server to T
           instead of the default, 2. Unlike +tries, this does not include the
           initial query.

       +[no]rrcomments
           Toggle the display of per-record comments in the output (for
           example, human-readable key information about DNSKEY records). The
           default is not to print record comments unless multiline mode is
           active.

       +[no]search
           Use [do not use] the search list defined by the searchlist or
           domain directive in resolv.conf (if any). The search list is not
           used by default.

           'ndots' from resolv.conf (default 1) which may be overridden by
           +ndots determines if the name will be treated as relative or not
           and hence whether a search is eventually performed or not.

       +[no]short
           Provide a terse answer. The default is to print the answer in a
           verbose form. This option always has global effect; it cannot be
           set globally and then overridden on a per-lookup basis.

       +[no]showsearch
           Perform [do not perform] a search showing intermediate results.

       +[no]sigchase
           This feature is now obsolete and has been removed; use delv
           instead.

       +split=W
           Split long hex- or base64-formatted fields in resource records into
           chunks of W characters (where W is rounded up to the nearest
           multiple of 4).  +nosplit or +split=0 causes fields not to be split
           at all. The default is 56 characters, or 44 characters when
           multiline mode is active.

       +[no]stats
           Toggles the printing of statistics: when the query was made, the
           size of the reply and so on. The default behavior is to print the
           query statistics as a comment after each lookup.

       +[no]subnet=addr[/prefix-length]
           Send (don't send) an EDNS Client Subnet option with the specified
           IP address or network prefix.

           dig +subnet=0.0.0.0/0, or simply dig +subnet=0 for short, sends an
           EDNS CLIENT-SUBNET option with an empty address and a source
           prefix-length of zero, which signals a resolver that the client's
           address information must not be used when resolving this query.

       +[no]tcflag
           Set [do not set] the TC (TrunCation) bit in the query. The default
           is +notcflag. This bit should be ignored by the server for QUERY.

       +[no]tcp
           Use [do not use] TCP when querying name servers. The default
           behavior is to use UDP unless a type any or ixfr=N query is
           requested, in which case the default is TCP. AXFR queries always
           use TCP.

       +timeout=T
           Sets the timeout for a query to T seconds. The default timeout is 5
           seconds. An attempt to set T to less than 1 will result in a query
           timeout of 1 second being applied.

       +[no]topdown
           This feature is related to dig +sigchase, which is obsolete and has
           been removed. Use delv instead.

       +[no]trace
           Toggle tracing of the delegation path from the root name servers
           for the name being looked up. Tracing is disabled by default. When
           tracing is enabled, dig makes iterative queries to resolve the name
           being looked up. It will follow referrals from the root servers,
           showing the answer from each server that was used to resolve the
           lookup.

           If @server is also specified, it affects only the initial query for
           the root zone name servers.

           +dnssec is also set when +trace is set to better emulate the
           default queries from a nameserver.

       +tries=T
           Sets the number of times to try UDP queries to server to T instead
           of the default, 3. If T is less than or equal to zero, the number
           of tries is silently rounded up to 1.

       +trusted-key=####
           Formerly specified trusted keys for use with dig +sigchase. This
           feature is now obsolete and has been removed; use delv instead.

       +[no]ttlid
           Display [do not display] the TTL when printing the record.

       +[no]ttlunits
           Display [do not display] the TTL in friendly human-readable time
           units of "s", "m", "h", "d", and "w", representing seconds,
           minutes, hours, days and weeks. Implies +ttlid.

       +[no]unexpected
           Accept [do not accept] answers from unexpected sources. By default,
           dig won't accept a reply from a source other than the one to which
           it sent the query.

       +[no]unknownformat
           Print all RDATA in unknown RR type presentation format (RFC 3597).
           The default is to print RDATA for known types in the type's
           presentation format.

       +[no]vc
           Use [do not use] TCP when querying name servers. This alternate
           syntax to +[no]tcp is provided for backwards compatibility. The
           "vc" stands for "virtual circuit".

       +[no]yaml
           Print the responses (and, if +qr is in use, also the outgoing
           queries) in a detailed YAML format.

       +[no]zflag
           Set [do not set] the last unassigned DNS header flag in a DNS
           query. This flag is off by default.

MULTIPLE QUERIES
       The BIND 9 implementation of dig supports specifying multiple queries
       on the command line (in addition to supporting the -f batch file
       option). Each of those queries can be supplied with its own set of
       flags, options and query options.

       In this case, each query argument represent an individual query in the
       command-line syntax described above. Each consists of any of the
       standard options and flags, the name to be looked up, an optional query
       type and class and any query options that should be applied to that
       query.

       A global set of query options, which should be applied to all queries,
       can also be supplied. These global query options must precede the first
       tuple of name, class, type, options, flags, and query options supplied
       on the command line. Any global query options (except +[no]cmd and
       +[no]short options) can be overridden by a query-specific set of query
       options. For example:

           dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr

       shows how dig could be used from the command line to make three
       lookups: an ANY query for www.isc.org, a reverse lookup of 127.0.0.1
       and a query for the NS records of isc.org. A global query option of +qr
       is applied, so that dig shows the initial query it made for each
       lookup. The final query has a local query option of +noqr which means
       that dig will not print the initial query when it looks up the NS
       records for isc.org.

IDN SUPPORT
       If dig has been built with IDN (internationalized domain name) support,
       it can accept and display non-ASCII domain names.  dig appropriately
       converts character encoding of domain name before sending a request to
       DNS server or displaying a reply from the server. If you'd like to turn
       off the IDN support for some reason, use parameters +noidnin and
       +noidnout or define the IDN_DISABLE environment variable.

FILES
       /etc/resolv.conf

       ${HOME}/.digrc

SEE ALSO
       delv(1), host(1), named(8), dnssec-keygen(8), RFC 1035.

BUGS
       There are probably too many query options.

AUTHOR
       Internet Systems Consortium, Inc.

COPYRIGHT
       Copyright (C) 2000-2011, 2013-2020 Internet Systems Consortium, Inc.
       ("ISC")

ISC                               2014-02-19                            DIG(1)
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